This application relates to non-invasive analysis. It also relates to utility patent application Ser. No. 11/025,698 filed on Dec. 12th. 2004 titled “Multiple Reference Non-invasive Analysis System” and to utility patent application Ser. No. 11/048,694 filed on Jan. 31 st. 2005 titled “Frequency Resolved Imaging system the contents of both of which are incorporated by reference as if fully set forth herein.
Non-invasive analysis, which for purposes of this application includes non-destructive analysis, is a valuable technique for acquiring information about systems or targets without undesirable side effects, such as damaging the system being analyzed. Non-invasive analysis has a broad range of applications including, non-destructive analysis of artifacts for defects, verification of the authenticity of documents, such as bank notes, bio-metric analysis and bio-medical analysis of living entities.
In the case of analyzing living entities, such as human tissue, undesirable side effects of invasive analysis include the risk of infection along with pain and discomfort associated with the invasive process.
The application of which this is a continuation-in-part, U.S. application Ser. No. 11/254,965 titled “Correlation of Concurrent Non-invasively Acquired Signals” (referenced above), describes a method, apparatus and system for non-invasive analysis that is suitable for determining attributes of targets, such as concentrations of specific components or analytes within a target, including the concentration of glucose within human tissue.
The invention includes an optical source and an optical processing system which provides probe and reference radiation. It also includes a means that applies the probe beam to the target to be analyzed, re-combines the probe and reference beams interferometrically, to generate concurrent interferometric signals which are detected and correlated with previously stored electronic data to determine an attribute of the target.
Frequently, such concurrently acquired signals are modified by various unwanted interfering effects of the environment in which the signals are acquired. Interfering effects include: relative motion between the target and the non-invasive analysis system; compression of the target; variations in the intensity of radiation scattered at the surface of the target; effectively introduce noise into the acquired signals.
The effective noise introduced by these interfering effects reduce the accuracy with which the sets of concurrently acquired signals can be correlated with data from a data bank stored in memory. Therefore there is an unmet need for a method, apparatus and system for reducing the influence of the interfering effects and increasing the accuracy of correlation of the sets of concurrently acquired data and thereby determining the attribute of a target with increased accuracy.